This invention relates to the chilling of food products in general, including meat, poultry, fish, fruits and vegetables and to the rapid and efficient freezing of such foodstuffs. Meat and poultry are frozen by air blast or liquid gas freezing methods utilizing liquid nitrogen or carbon dioxide. Aqueous media have also been proposed as freezants in an attempt to achieve a high rate of freezing along with minimal expense. Cryogenic freezing provides a rapid rate of cooling but the cost is substantial. Air blast chilling on the other hand is fairly economical but the cost mounts quickly since it requires long periods of time to attain desired low temperatures. Liquids such as aqueous solutions containing calcium chloride, ethylene glycol and propylene glycol as freezing point depressants have also been proposed. These, however, have not been favorably received since they present problems with handling of such solutions (high viscosity) or they contaminate the food with objectionable medicinal or other flavors and aftertastes.
Accordingly, it is an object of this invention to provide a freezant and a method for using said freezant in the rapid, economical, chilling of foodstuffs to low temperatures without adversely affecting said foodstuffs organoleptically or otherwise.
Another object of the invention is to provide a method for freezing poultry and meat with a solution having a freezing point below -5.degree. F., yet having a viscosity sufficiently low to allow for easy pumping of said solution and ease of handling and contacting of such meat and poultry with the solution.
In U.S. Pat. No. 4,601,909, which issued Jul. 22, 1986 to Kazunori Nagoshi, a method of freezing fishery products is described. The process involves cooling a brine of 10% calcium chloride, water, 40% propylene glycol and rapeseed oil to between -30.degree. C. (-22.degree. F.) and -42.degree. C. (-43.6.degree. F.) and immersing the fish in the brine until frozen. Not mentioned is the high viscosity of the solution resultingfrom the large quantity of propylene glycol and the bitterness of the resulting product imparted by calcium chloride. Accordingly, it is an object of this invention to provide a low viscosity freezant free of pumping limitations and also without the objectionable flavor characteristics of Nagoshi.
In the article "Freezing of Vegetables By Direct Contact With Aqueous Solutions of Ethanol And Sodium Chloride" in Journal of Food Science Vol. 42, No. 4 (1977), pages 911-916, J. C. Cipolletti, et al., describe the use of aqueous freezants in lowering the temperature of carrots, corn, peas, and beans by direct contact freezing. The freezant is made up of 15% sodium chloride, 15% ethanol and the remainder water. The maximum depression of freezing point is around -20.degree. F. A shortcoming of the Cipolletti, et al. process is the medicinal taste imparted to the product by ethanol. Accordingly, it is another object of this invention to provide a more efficient freezant capable of more rapidly despressing the temperature of the foodstuff with which it is contacted, yet which has low viscosity, flavor suitability, and favorable cost characteristics.
Additional objects of the invention, if not specifically set forth herein, will be readily apparent to those skilled in the art from a reading of the following detailed description of the invention.